Desktop folder locked, strange icon

[Darth.Titan]

My brother is running on a 2011 27 inch iMac running the latest version of El Capitan.
He's having an issue with the Desktop folder locking itself. He can go to 'Get Info' and unlock it, and his problems are solved for a while, but the directory re-locks itself after a while.

Another odd thing is the icon on the folder. It's not even a proper El Capitan folder icon.

We've tried Disk Utility and even ran Malwarebytes on it, but are at a loss. Anyone seen this icon before?

 

[Weaselboy]

That definitely looks like some sort of third party utility he installed that is doing that. OS X can't generate that icon on its own.

Try running the app Etrecheck once. It will create a report showing all third party apps and hidden launch items that might be running and doing this. The report is anonymized, so you can post it here is you would like others to take a look.